Which feature distinguishes formal correspondence from informal correspondence? contractions, slang, personal tone, complex sentence.

Slang

Explanation:

Whilst formal correspondence may share similarities with informal correspondence such as the use of personal tones, contractions and complex sentences, the key distinguishing feature is slang.

Slang may be used in informal communication but never in formal. Slang is therefore chiefly for colloquial use. It is worthy of note that slang is not meant to refer to swear words alone. Slang refers to any word that is not to be used in formal correspondence for instance, y'all is considered slang.

no

the answer is b to the question